This application for a Mentored Patient-Oriented Research Career Development Award entitled Circadian Timing, Sleep, and Adiposity is being submitted by Dr. Kelly Glazer Baron, PhD, MPH, to continue her professional development as a clinical researcher in sleep and circadian rhythms. Obesity is one of the nation's greatest health problems and sleep and circadian rhythm disturbances are thought to play a role in the development of obesity. Short sleep duration and poor sleep quality have been shown to affect metabolism and the hormones that regulate hunger and satiety. In addition, disrupted circadian rhythms, such as in shift work, have been associated with weight gain, increased risk for metabolic syndrome, poorer diet and exercise behavior. At this point, it is not known to what degree individual differences in circadian timing contribute to obesity in non-shift workers. This study will test the timing of circadian rhythms and also the alignment between circadian rhythms and sleep with measures of adiposity, dietary behavior, and physical activity. Results of this study may lead to new interventions for the prevention and treatment of obesity. Dr. Baron is a Clinical Health Psychologist with a specialty in Behavioral Sleep Medicine. Her research has focused on health behaviors in sleep disorders populations, including treatment adherence in obstructive sleep apnea and outcomes of insomnia treatment. She has been building her knowledge and experience with circadian rhythms research through evaluating dietary behavior in individuals with normal and delayed sleep timing preferences. The project proposed in this award builds on Dr. Baron's prior research demonstrating greater calorie intake in those with a preference for later sleep timing by objectively measuring circadian rhythms and also exploring the effects of misalignment between circadian rhythms and sleep. Her long term goals are to become an expert on the role of circadian rhythms in metabolism and weight regulation, with understanding of both the biological and social aspects of this relationship. It is Dr. Baron's hope that this work will lead to interventions to prevent and treat obesity through new mechanisms, such as shifting circadian rhythms using behavioral changes, light and melatonin.